Transcriptome characterization of candidate genes related to chromium uptake, transport and accumulation in Miscanthus sinensis

Miscanthus sinensis is a C4 perennial grass species that is widely used as forage, ornamental grass and bioenergy crop due to its broad adaption and great biological traits. Recent studies indicated that M. sinensis could also grow in marginal lands which were contaminated with heavy metals, and exhibited important ecological restoration potential. In this study, transcriptome characterization of candidate genes related to chromium (Cr) uptake, transport and accumulation in M. sinensis were employed to investigate the molecular mechanism of plant tolerance to heavy metal stress. The result showed that following treatment of 200 mg/L of Cr, plant roots could accumulate most Cr and localize mainly in cell walls and soluble fractions, whereas Cr in stems and leaves was primarily in soluble fractions. A total of 83,645 differentially expressed genes (DEGs) were obtained after the treatment. Many genes involved in heavy metal transport, metal ion chelation and photosynthesis were found to be Cr-induced DEGs. Co-expression and weighted correlation network analysis revealed that Glutathion metabolism and ABC transporters pathways play an important role in Cr tolerance of M. sinensis. A hypothesis schematic diagram for the Cr uptake, transport and accumulation of M. sinensis cells were suggested, which could provide a molecular and genetic basis for future candidate genes validation and breeding of such crops.